The present invention relates to a power management control system (PMCS), and more particularly relates to an improved client/server communication interface for a PMCS.
PMCS's allow an operator to monitor and control a variety of intelligent electronic devices within an electrical distribution system. Such devices can include relays, meters, switches, etc., which may be mounted within a common switchgear cabinet to create a control panel. One such PMCS is described in U.S. Pat. No. 5,862,391 entitled “Power Management Control System.”
One PMCS tool, such as General Electric's Waveform Capture, a POWER LEADER™ PMCS tool, for examining current and voltage waveforms and the associated harmonic data of selected devices within the system, helps to increase productivity, reduce downtime, and improve power quality. By selecting voltage and current waveforms, an operator can use such a waveform capture tool to examine selected devices in the system. The waveform capture tool uses the PMCS power management network to retrieve captured and recorded waveform data from power management devices.
General Electric's Waveform Capture application is a Windows NT™-based package that currently communicates with the PMCS Dynamic Data Exchange (DDE) server. The PMCS DDE server is a Microsoft® Windows NT™ application that allows other Windows NT™ applications (clients) to access data from General Electric Co. and other third-party devices.
The waveform capture software consists of two components, the Waveform Server (“WFS”) and the Waveform Client (“WFC”). A request for a waveform for a particular device is entered at the WFC. The WFC passes this request to the WFS (for most PMCS devices) or to the GE 7700 Gateway Server (for the EPM 7700). The WFS in turn passes the request to the PMCS DDE Server, which issues the command to the device, collects the necessary data and passes the data back to the WFS. The GE 7700 Gateway Server collects its data from the PML Pegasys Comm Server. Once the Gateway or WFS receives the data in response to its request, it collates the data into a file for viewing at the WFC.
Customers who use the existing WFC/WFS DDE communications interface are limited by industry standards to employing the NetBEUI protocol as the basis for DDE communications. NetBEUI is the protocol stack that comes with IBM® and Microsoft® LAN products. NetBEUI, however, lacks a network layer and is weak in the area of security. NetBEUI is a component of Microsoft® Windows NT™ operating system and it limits communication between distributed software applications to single network segments. As a result, distributed WFC and WFS applications are limited to operation on a single network segment. Customers with extensive network installations with multiple segments (routers) cannot operate the existing WFC/WFS applications on their topology. In addition, customers who desired to have their PMCS operate as NT Services (for increased security and automatic startup) could not be given this capability because of the limitations of the current DDE communication scheme.
Other vendors who use DDE in their applications have incorporated enhancements to the DDE protocol within their applications in order to circumvent the indicated limitations of NetBEUI. For example, Wonderware's InTouch Suite Link is an alternative based on TCP/IP and supports the server-topic-item model of DDE, thus maintaining the appearance of a DDE interface.